Understanding the mechanisms of axonal transport of neurotropic viruses is the key to understanding and controlling their spread in the nervous system. To multiply and spread, to move initially from the site of entry and later to the site of release, Herpes simplex virus (HSV) must use neuronal host cell proteins and mechanisms. Our understanding of the interplay of specific viral proteins that piggyback on the mechanisms and of the neuronal proteins that are exploited, is critical but almost nonexistent. In this application we continue to focus on the anterograde transport of HSV. Based on our previous results, our hypothesis is that the nucleocapsid and envelope components of HSV are independently transported in the axon and that the components require specific kinesin related proteins. 1) We have begun to examine the transport of the nucleocapsid and envelope components. To do this we have developed two viral mutant strains and revertants that will facilitate our research into these transport mechanisms. 2) In this proposal we shall continue these studies and carry out co-immunoprecipitation assays to identify the motor proteins associated with the nucleocapsid component. 3) We shall also determine whether or not the virus egresses from the cell by budding, after the envelope proteins are delivered to the axon membrane and the nucleocapsids cluster near that region of membrane. These results will provide important new cell biological information about the recognition signals of particular organelles. They will also have significant clinical benefits. The anterograde transport of HSV to the cornea in human herpetic keratitis results in severe consequences, including corneal scars, glaucoma and possibly encephalitis. Our results will provide new insight into the identification of viral and host proteins necessary for viral envelope and nucleocapsid transport and a rational basis for the design of innovative antiviral drugs for prevention and intervention. Furthermore, the genome of HSV can be altered to serve as a vector for introduction of novel genes into the nervous system. Our results will elucidate the mechanisms that target the vector to particular neuron types and to particular regions of infected neurons.